Fix work item counts

Issue: Work item consolidate list count not formatted ... (#580022 - closed)

What does this MR do and why?

The initial fix MR did not work: Format work items count (!214236 - merged) because of Duo's suggested change on that MR which was applied without validating it.

Hence in this MR we are reverting that change and going back to the original approach to fix this issue.

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Fixes a bug for work item counts displayed as raw values. Now large numbers are formatted with commas, instead of showing "1000 items", it will now display "1,000 items" for better readability.

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Turn on FF work_item_planning_view
• Go to the group consolidated list page e.g http://gdk.test:3000/groups/twitter/-/work_items
• Local gdk probably doesn't have enough seed data (issues/epics) to display the formatted count, so in order to validate this do the following:
• Manually edit app/assets/javascripts/work_items/pages/work_items_list_app.vue:921 and replace formatNumber(this.workItemsCount) -> formatNumber(10234)
• Verify in the browser that the count is displayed with commas

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